Modern agriculture techniques require that during separation of a corn plant ear (or “ear”) from a corn plant or corn plant stalk (or “stalk”), corn harvesting machines optimize the following considerations: (1) increase the rate of ear separation; (2) increase the speed at which stalks are ejected from the row unit; (3) retain minimal amounts of material other than ears (“MOTE”) in the heterogeneous material being delivered to the harvesting machine for threshing; and, (4) lacerate, cut, and/or penetrate the shell of the stalk to expose the internal portions for accelerated decomposition of the stalk.
As shown in FIG. 1, modern corn headers are provided with a plurality of row crop dividers for retrieving, lifting, and directing the rows of stalks toward their respective corn plant engagement chambers. The corn plant engagement chamber is defined herein as the portion of the corn head row unit that engages the stalk and separates the ear from the corn plant. FIG. 1A shows the top view of two stalk rolls found in the prior art. Gathering chains located in the corn plant engagement chamber draw the stalks and/or ears towards the header. Stalk rolls located beneath the gathering chains pull the stalks rapidly downward, returning the stalk to the field. These stalk rolls are typically powered by a gearbox. As the stalk rolls rotate, the flutes on the stalk rolls engage and pull the stalks downward. Two stripper plates located above the stalk rolls, with one stripper plate on either side of the corn row, are spaced wide enough to allow the stalks and leaves to pass between them but narrow enough to retain the ears. This causes the ears to be separated from the corn plant as the stalk is pulled down through the stripper plates. The stalk rolls continue to rotate and eject the unwanted portions of the corn plant below the corn plant engagement chamber, thereby returning the unwanted portions of the corn plant to the field.
The performance of stalk rolls found in the prior art, as shown in FIGS. 3-5, has been found to be less than optimal. Attempts at increasing stalk roll performance and increasing ear separation speed have been made by increasing rotational speed of the stalk rolls. These attempts have been largely unsuccessful because stalk rolls having uniform length flutes rotating at high speeds simulate a solid rotating cylinder (sometimes referred to as an “egg-beater effect”), which restricts entry of the corn plant into the corn plant engagement chamber. The diameter of the simulated rotating cylinder is approximately equal to the distance from the tip of a first flute on a given stalk roll to the tip of a second flute oriented closest to 180 degrees from the first flute (i.e., two opposed flutes on a given stalk roll). This rotating-cylinder effect prevents individual flutes from engaging the stalk and restricts corn plants from entering the corn plant engagement chamber. Thus, stalk engagement is hindered and the corn plant hesitates and does not enter the corn plant engagement chamber.
The prior art has attempted to increase the performance of cutting or chopping stalk rolls by simply adding more flutes to the stalk rolls. In prior art applications, this reduces the performance of the stalk rolls because during rotation of the stalk rolls, a semi-continuous wall of steel restricts entry of the stalk into the corn plant engagement chamber, as noted above. Adding flutes decreases the likelihood of a stalk entering the space between two opposing stalk rolls. That is, as more flutes are added to the stalk roll, rotation of the stalk roll causes the stalk roll to more closely simulate a rotating cylinder. When viewed along the axis of rotation of the stalk roll (the direction from which the stalk rolls would approach the stalk), adding more flutes restricts the ability of the stalks to enter the corn plant engagement chamber due to interference from the ends of the flutes.
When the gathering chain paddle passes above the stripper plates and engages a stalk that is restricted from entering the corn plant engagement chamber, the gathering chain paddle will likely break or sever the stalk prior to ear separation. Stalk severance prior to ear separation increases intake of MOTE to the harvesting machine, thereby increasing horsepower and fuel requirements. Difficulty in stalks entering the area between to stalk rolls may also cause ear separation to take place near the opening of the row unit and allow loose ears to fall to the ground, thereby becoming irretrievable.
FIG. 3 shows prior art opposing stalk roll designs utilizing six flutes that inter-mesh and overlap. When the flutes of this type engage the stalk, the flutes alternately apply opposing force. This knife-edge relationship causes at least two problems. First, the corn plants are violently tossed from side to side causing premature separation of loosely attached ears, thereby permitting the ear to fall to the ground and become irretrievable. Second, the stalk is cut or snapped at a node causing long, unwanted portions of the stalk and leaves to stay attached to the ear and remain in the row unit. This increases the amount of MOTE the harvesting machine must process. This problem is compounded as the number of row units per corn head is increased.
FIG. 4 shows the prior art stalk roll design with intermeshing knife edges as described in U.S. Pat. No. 5,404,699. As shown, the stalk rolls have six outwardly extending integral flutes. Each flute has a knife edge that is provided with a leading surface and a trailing surface. The leading surface of the knife edge has a ten degree forward (with respect to the rotation of the stalk roll) slope and the trailing surface has a thirty degree reverse slope (with respect to the rotation of the stalk roll), both of which slopes are defined with respect to a line extending through the vertex of the knife edge and the central longitudinal axis of the stalk roll. Therefore, the leading surface is steeper than the trailing surface of each knife edge. The radially extending flutes are interleaved with one another in an intermeshing-type arrangement. The stalk rolls may be mounted in a cantilevered arrangement; or alternatively, in an arrangement employing nose bearings. The stalk roll comprises a cylindrical shell formed by two semi-cylindrical pieces that are clamped about a drive shaft. Bolts extend between the two semi-cylindrical pieces to pull the pieces together, thereby clamping the stalk rolls to the drive shaft.
This design, upon restricted engagement of the stalk roll with the stalk, allows the knife edges to cut stalks before pulling the stalks through the stripper plates to separate the ear from the stalk, effectively leaving the upper portion of the corn plant free to float in the corn row unit as shown in FIG. 3. This requires the harvesting machine threshing components to process a substantial portion of the stalk, which increases harvesting machine horsepower and fuel requirements.
FIG. 5 shows the design disclosed by U.S. Pat. No. 6,216,428, which is a stalk roll having bilaterally symmetric flutes with knife edges that are adjacent and overlap in the shear zone area. This design produces a shearing and cutting of the stalk using a scissor configuration produced by the leading and trailing edges of the opposing knife-edged flutes. Again, the stalks are cut off prior to ear separation. This is sometimes referred to as a “scissor effect” and also results in the need to process increased amounts of MOTE.
Case IH corn heads built prior to development of U.S. Pat. No. 6,216,428 used stalk rolls having four knives that are bolted to a solid shaft. Adjacent stalk rolls are registered with one another so that as the stalk rolls are rotated, the knives of the opposing stalk rolls are also opposing rather than intermeshing. In an opposing arrangement, the knives come into contact with opposite sides of the stalk at the same general height of the stalk, thereby lacerating the stalk for accelerated decomposition. It is important that the blades are correctly registered with one another, and that the blades are correctly spaced from one another. The stalk rolls used on Case IH corn heads require nose bearings at the forward end (with respect to the direction of travel of the harvesting machine during threshing) of the stalk rolls to operate properly and may not be mounted in a cantilevered arrangement.